Jan Dubois > Win32-OLE > Win32::OLE::Variant

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NAME ^

Win32::OLE::Variant - Create and modify OLE VARIANT variables

SYNOPSIS ^

        use Win32::OLE::Variant;
        my $var = Variant(VT_DATE, 'Jan 1,1970');
        $OleObject->{value} = $var;
        $OleObject->Method($var);

DESCRIPTION ^

The IDispatch interface used by the Perl OLE module uses a universal argument type called VARIANT. This is basically an object containing a data type and the actual data value. The data type is specified by the VT_xxx constants.

Functions

nothing()

The nothing() function returns an empty VT_DISPATCH variant. It can be used to clear an object reference stored in a property

        use Win32::OLE::Variant qw(:DEFAULT nothing);
        # ...
        $object->{Property} = nothing;

This has the same effect as the Visual Basic statement

        Set object.Property = Nothing

The nothing() function is not exported by default.

nullstring()

The nullstring() function returns a VT_BSTR variant with a NULL string pointer. This is not the same as a VT_BSTR variant with an empty string "". The nullstring() value is the same as the vbNullString constant in Visual Basic.

The nullstring() function is not exported by default.

Variant(TYPE, DATA)

This is just a function alias of the Win32::OLE::Variant-new()> method (see below). This function is exported by default.

Methods

new(TYPE, DATA)

This method returns a Win32::OLE::Variant object of the specified TYPE that contains the given DATA. The Win32::OLE::Variant object can be used to specify data types other than IV, NV or PV (which are supported transparently). See Variants below for details.

For VT_EMPTY and VT_NULL variants, the DATA argument may be omitted. For all non-VT_ARRAY variants DATA specifies the initial value.

To create a SAFEARRAY variant, you have to specify the VT_ARRAY flag in addition to the variant base type of the array elements. In this cases DATA must be a list specifying the dimensions of the array. Each element can be either an element count (indices 0 to count-1) or an array reference pointing to the lower and upper array bounds of this dimension:

        my $Array = Win32::OLE::Variant->new(VT_ARRAY|VT_R8, [1,2], 2);

This creates a 2-dimensional SAFEARRAY of doubles with 4 elements: (1,0), (1,1), (2,0) and (2,1).

A special case is the creation of one-dimensional VT_UI1 arrays with a string DATA argument:

        my $String = Variant(VT_ARRAY|VT_UI1, "String");

This creates a 6 element character array initialized to "String". For backward compatibility VT_UI1 with a string initializer automatically implies VT_ARRAY. The next line is equivalent to the previous example:

        my $String = Variant(VT_UI1, "String");

If you really need a single character VT_UI1 variant, you have to create it using a numeric intializer:

        my $Char = Variant(VT_UI1, ord('A'));
As(TYPE)

As converts the VARIANT to the new type before converting to a Perl value. This take the current LCID setting into account. For example a string might contain a ',' as the decimal point character. Using $variant-As(VT_R8)> will correctly return the floating point value.

The underlying variant object is NOT changed by this method.

ChangeType(TYPE)

This method changes the type of the contained VARIANT in place. It returns the object itself, not the converted value.

Copy([DIM])

This method creates a copy of the object. If the original variant had the VT_BYREF bit set then the new object will contain a copy of the referenced data and not a reference to the same old data. The new object will not have the VT_BYREF bit set.

        my $Var = Variant(VT_I4|VT_ARRAY|VT_BYREF, [1,5], 3);
        my $Copy = $Var->Copy;

The type of $Copy is now VT_I4|VT_ARRAY and the value is a copy of the other SAFEARRAY. Changes to elements of $Var will not be reflected in $Copy and vice versa.

The Copy method can also be used to extract a single element of a VT_ARRAY | VT_VARIANT object. In this case the array indices must be specified as a list DIM:

        my $Int = $Var->Copy(1, 2);

$Int is now a VT_I4 Variant object containing the value of element (1,2).

Currency([FORMAT[, LCID]])

This method converts the VARIANT value into a formatted currency string. The FORMAT can be either an integer constant or a hash reference. Valid constants are 0 and LOCALE_NOUSEROVERRIDE. You get the value of LOCALE_NOUSEROVERRIDE from the Win32::OLE::NLS module:

        use Win32::OLE::NLS qw(:LOCALE);

LOCALE_NOUSEROVERRIDE tells the method to use the system default currency format for the specified locale, disregarding any changes that might have been made through the control panel application.

The hash reference could contain the following keys:

        NumDigits       number of fractional digits
        LeadingZero     whether to use leading zeroes in decimal fields
        Grouping        size of each group of digits to the left of the decimal
        DecimalSep      decimal separator string
        ThousandSep     thousand separator string
        NegativeOrder   see L<Win32::OLE::NLS/LOCALE_ICURRENCY>
        PositiveOrder   see L<Win32::OLE::NLS/LOCALE_INEGCURR>
        CurrencySymbol  currency symbol string

For example:

        use Win32::OLE::Variant;
        use Win32::OLE::NLS qw(:DEFAULT :LANG :SUBLANG :DATE :TIME);
        my $lcidGerman = MAKELCID(MAKELANGID(LANG_GERMAN, SUBLANG_NEUTRAL));
        my $v = Variant(VT_CY, "-922337203685477.5808");
        print $v->Currency({CurrencySymbol => "Tuits"}, $lcidGerman), "\n";

will print:

        -922.337.203.685.477,58 Tuits
Date([FORMAT[, LCID]])

Converts the VARIANT into a formatted date string. FORMAT can be either one of the following integer constants or a format string:

        LOCALE_NOUSEROVERRIDE   system default date format for this locale
        DATE_SHORTDATE          use the short date format (default)
        DATE_LONGDATE           use the long date format
        DATE_YEARMONTH          use the year/month format
        DATE_USE_ALT_CALENDAR   use the alternate calendar, if one exists
        DATE_LTRREADING         left-to-right reading order layout
        DATE_RTLREADING         right-to left reading order layout

The constants are available from the Win32::OLE::NLS module:

        use Win32::OLE::NLS qw(:LOCALE :DATE);

The following elements can be used to construct a date format string. Characters must be specified exactly as given below (e.g. "dd" not "DD"). Spaces can be inserted anywhere between formatting codes, other verbatim text should be included in single quotes.

        d       day of month
        dd      day of month with leading zero for single-digit days
        ddd     day of week: three-letter abbreviation (LOCALE_SABBREVDAYNAME)
        dddd    day of week: full name (LOCALE_SDAYNAME)
        M       month
        MM      month with leading zero for single-digit months
        MMM     month: three-letter abbreviation (LOCALE_SABBREVMONTHNAME)
        MMMM    month: full name (LOCALE_SMONTHNAME)
        y       year as last two digits
        yy      year as last two digits with leading zero for years less than 10
        yyyy    year represented by full four digits
        gg      period/era string

For example:

        my $v = Variant(VT_DATE, "April 1 99");
        print $v->Date(DATE_LONGDATE), "\n";
        print $v->Date("ddd',' MMM dd yy"), "\n";

will print:

        Thursday, April 01, 1999
        Thu, Apr 01 99
Dim()

Returns a list of array bounds for a VT_ARRAY variant. The list contains an array reference for each dimension of the variant's SAFEARRAY. This reference points to an array containing the lower and upper bounds for this dimension. For example:

        my @Dim = $Var->Dim;

Now @Dim contains the following list: ([1,5], [0,2]).

Get(DIM)

For normal variants Get returns the value of the variant, just like the Value method. For VT_ARRAY variants Get retrieves the value of a single array element. In this case DIM must be a list of array indices. E.g.

        my $Val = $Var->Get(2,0);

As a special case for one dimensional VT_UI1|VT_ARRAY variants the Get method without arguments returns the character array as a Perl string.

        print $String->Get, "\n";
IsNothing()

Tests if the object is an empty VT_DISPATCH variant. See also nothing().

IsNullString()

Tests if the object is an empty VT_BSTR variant. See also nullstring().

LastError()

The use of the Win32::OLE::Variant-LastError()> method is deprecated. Please use the Win32::OLE-LastError()> class method instead.

Number([FORMAT[, LCID]])

This method converts the VARIANT value into a formatted number string. The FORMAT can be either an integer constant or a hash reference. Valid constants are 0 and LOCALE_NOUSEROVERRIDE. You get the value of LOCALE_NOUSEROVERRIDE from the Win32::OLE::NLS module:

        use Win32::OLE::NLS qw(:LOCALE);

LOCALE_NOUSEROVERRIDE tells the method to use the system default number format for the specified locale, disregarding any changes that might have been made through the control panel application.

The hash reference could contain the following keys:

        NumDigits       number of fractional digits
        LeadingZero     whether to use leading zeroes in decimal fields
        Grouping        size of each group of digits to the left of the decimal
        DecimalSep      decimal separator string
        ThousandSep     thousand separator string
        NegativeOrder   see L<Win32::OLE::NLS/LOCALE_INEGNUMBER>
Put(DIM, VALUE)

The Put method is used to assign a new value to a variant. The value will be coerced into the current type of the variant. E.g.:

        my $Var = Variant(VT_I4, 42);
        $Var->Put(3.1415);

This changes the value of the variant to 3 because the type is VT_I4.

For VT_ARRAY type variants the indices for each dimension of the contained SAFEARRAY must be specified in front of the new value:

        $Array->Put(1, 1, 2.7);

It is also possible to assign values to *every* element of the SAFEARRAY at once using a single Put() method call:

        $Array->Put([[1,2], [3,4]]);

In this case the argument to Put() must be an array reference and the dimensions of the Perl list-of-lists must match the dimensions of the SAFEARRAY exactly.

The are a few special cases for one-dimensional VT_UI1 arrays: The VALUE can be specified as a string instead of a number. This will set the selected character to the first character of the string or to '\0' if the string was empty:

        my $String = Variant(VT_UI1|VT_ARRAY, "ABCDE");
        $String->Put(1, "123");
        $String->Put(3, ord('Z'));
        $String->Put(4, '');

This will set the value of $String to "A1CZ\0". If the index is omitted then the string is copied to the value completely. The string is truncated if it is longer than the size of the VT_UI1 array. The result will be padded with '\0's if the string is shorter:

        $String->Put("String");

Now $String contains the value "Strin".

Put returns the Variant object itself so that multiple Put calls can be chained together:

        $Array->Put(0,0,$First_value)->Put(0,1,$Another_value);
Time([FORMAT[, LCID]])

Converts the VARIANT into a formatted time string. FORMAT can be either one of the following integer constants or a format string:

        LOCALE_NOUSEROVERRIDE   system default time format for this locale
        TIME_NOMINUTESORSECONDS don't use minutes or seconds
        TIME_NOSECONDS          don't use seconds
        TIME_NOTIMEMARKER       don't use a time marker
        TIME_FORCE24HOURFORMAT  always use a 24-hour time format

The constants are available from the Win32::OLE::NLS module:

        use Win32::OLE::NLS qw(:LOCALE :TIME);

The following elements can be used to construct a time format string. Characters must be specified exactly as given below (e.g. "dd" not "DD"). Spaces can be inserted anywhere between formatting codes, other verbatim text should be included in single quotes.

        h       hours; 12-hour clock
        hh      hours with leading zero for single-digit hours; 12-hour clock
        H       hours; 24-hour clock
        HH      hours with leading zero for single-digit hours; 24-hour clock
        m       minutes
        mm      minutes with leading zero for single-digit minutes
        s       seconds
        ss      seconds with leading zero for single-digit seconds
        t       one character time marker string, such as A or P
        tt      multicharacter time marker string, such as AM or PM

For example:

        my $v = Variant(VT_DATE, "April 1 99 2:23 pm");
        print $v->Time, "\n";
        print $v->Time(TIME_FORCE24HOURFORMAT|TIME_NOTIMEMARKER), "\n";
        print $v->Time("hh.mm.ss tt"), "\n";

will print:

        2:23:00 PM
        14:23:00
        02.23.00 PM
Type()

The Type method returns the variant type of the contained VARIANT.

Unicode()

The Unicode method returns a Unicode::String object. This contains the BSTR value of the variant in network byte order. If the variant is not currently in VT_BSTR format then a VT_BSTR copy will be produced first.

Value()

The Value method returns the value of the VARIANT as a Perl value. The conversion is performed in the same manner as all return values of Win32::OLE method calls are converted.

Overloading

The Win32::OLE::Variant package has overloaded the conversion to string and number formats. Therefore variant objects can be used in arithmetic and string operations without applying the Value method first.

Class Variables

The Win32::OLE::Variant class used to have its own set of class variables like $CP, $LCID and $Warn. In version 0.1003 and later of the Win32::OLE module these variables have been eliminated. Now the settings of Win32::OLE are used by the Win32::OLE::Variant module too. Please read the documentation of the Win32::OLE-&gt;Option class method.

Constants

These constants are exported by default:

        VT_EMPTY
        VT_NULL
        VT_I2
        VT_I4
        VT_R4
        VT_R8
        VT_CY
        VT_DATE
        VT_BSTR
        VT_DISPATCH
        VT_ERROR
        VT_BOOL
        VT_VARIANT
        VT_UNKNOWN
        VT_DECIMAL
        VT_UI1

        VT_ARRAY
        VT_BYREF

VT_DECIMAL is not on the official list of allowable OLE Automation datatypes. But even Microsoft ADO seems to sometimes return values of Recordset fields in VT_DECIMAL format.

Variants

A Variant is a data type that is used to pass data between OLE connections.

The default behavior is to convert each perl scalar variable into an OLE Variant according to the internal perl representation. The following type correspondence holds:

        C type          Perl type       OLE type
        ------          ---------       --------
          int              IV            VT_I4
        double             NV            VT_R8
        char *             PV            VT_BSTR
        void *           ref to AV       VT_ARRAY
           ?              undef          VT_ERROR
           ?        Win32::OLE object    VT_DISPATCH

Note that VT_BSTR is a wide character or Unicode string. This presents a problem if you want to pass in binary data as a parameter as 0x00 is inserted between all the bytes in your data. The Variant() method provides a solution to this. With Variants the script writer can specify the OLE variant type that the parameter should be converted to. Currently supported types are:

        VT_UI1     unsigned char
        VT_I2      signed int (2 bytes)
        VT_I4      signed int (4 bytes)
        VT_R4      float      (4 bytes)
        VT_R8      float      (8 bytes)
        VT_DATE    OLE Date
        VT_BSTR    OLE String
        VT_CY      OLE Currency
        VT_BOOL    OLE Boolean

When VT_DATE and VT_CY objects are created, the input parameter is treated as a Perl string type, which is then converted to VT_BSTR, and finally to VT_DATE of VT_CY using the VariantChangeType() OLE API function. See "EXAMPLES" in Win32::OLE for how these types can be used.

Variant arrays

A variant can not only contain a single value but also a multi-dimensional array of values (called a SAFEARRAY). In this case the VT_ARRAY flag must be added to the base variant type, e.g. VT_I4 | VT_ARRAY for an array of integers. The VT_EMPTY and VT_NULL types are invalid for SAFEARRAYs. It is possible to create an array of variants: VT_VARIANT | VT_ARRAY. In this case each element of the array can have a different type (including VT_EMPTY and VT_NULL). The elements of a VT_VARIANT SAFEARRAY cannot have either of the VT_ARRAY or VT_BYREF flags set.

The lower and upper bounds for each dimension can be specified separately. They do not have to have all the same lower bound (unlike Perl's arrays).

Variants by reference

Some OLE servers expect parameters passed by reference so that they can be changed in the method call. This allows methods to easily return multiple values. There is preliminary support for this in the Win32::OLE::Variant module:

        my $x = Variant(VT_I4|VT_BYREF, 0);
        my $y = Variant(VT_I4|VT_BYREF, 0);
        $Corel->GetSize($x, $y);
        print "Size is $x by $y\n";

After the GetSize method call $x and $y will be set to the respective sizes. They will still be variants. In the print statement the overloading converts them to string representation automatically.

VT_BYREF is now supported for all variant types (including SAFEARRAYs). It can also be used to pass an OLE object by reference:

        my $Results = $App->CreateResultsObject;
        $Object->Method(Variant(VT_DISPATCH|VT_BYREF, $Results));

AUTHORS/COPYRIGHT ^

This module is part of the Win32::OLE distribution.

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